Thyristors,SCR,Diac,Triac,UJT theory

[walters]

diac theory

What are Thyristors,SCR,Diac,Triac,UJT used for?

How do i use a Thyristor?
How do i use a SCR?
How do i use a Diac?
How do i use a Triac?
How do i use a UJT?

What type or circuits use them ?

What kind of Applications can i use these components for?

 

[usernam]

scr diac triac

I think this shud answer your questions.
h*tp://en.wikipedia.org/wiki/Thyristors

 

[walters]

diac wikipedia

can u please give me examples of how these components are used?

 

[usernam]

ujt theory

Well thyristors for example are used in controlled rectifiers. In uncontrolled rectifiers u use diodes and in controlled rectifiers where you may want to control the dc o/p voltage level you can use thyristors in place of the diodes. Basically thyristors are used where there is a need for lower freq and higher power devices.
Triacs are used where u mite need dual direction conduction. For example if yu want to control the amount of power available to a light bulb. You could use the triac and by firing the triac on at different instances u control the bulb brightness.
One main use of UJTs is as a trigger device for thyristors.
Diacs are typically used for triggering triacs.